Due to the ever advancing miniaturization in the semiconductor industry, no longer is only the alignment of the wafers to one another critical, especially with respect to the 3D technology which has become more and more important, but also the changes in shape which occur due to treatment of the wafers, especially parallel to the wafer surface.
Mainly in bonding technology are alignment precision and thus bonding precision as high as possible critical due to the structures which are becoming continually smaller. The problem of exact alignment of two structures prior to the bonding process to one another has already been successfully solved by different techniques. But it has been shown that during the bonding process distortions of the touching structures to one another can also occur. Furthermore, structures based on other physical parameters can be shifted relative to one another after a bonding process has already been carried out. Due to these shifts or distortions, a repeated or intensified deviation of the previously very good alignment precision occurs, especially after an already completed bonding process. Existing prior art encompasses mainly measurement devices which traverse two surfaces with respect to a coordinate system defined in a fixed manner, note the positions of the structures on the surface, and after the corresponding bond process repeat the measurement in order to obtain information about the distortions.
The measurement of individual structures on the substrate surface before and after treatment of the substrate is very complex and is associated with corresponding costs.
An advantage of this invention is a device and a method for determining changes in the shape of a substrate parallel to its substrate surface, wherein the determination takes place promptly, with high precision, reliably and economically.
This advantage is achieved with the features of the claimed subject matter. Advantageous developments of the invention are given in the dependent claims. All combinations of at least two of the features given in the specification, the claims and/or the figures also fall within the scope of the invention. At the given value ranges, values within the indicated limits will also be considered to be disclosed as boundary values and will be claimed in any combination.